1. Field of the Invention
This invention relates generally to water heating, and is more particularly concerned with an efficient flue for use in a gas water heater or the like.
2. Discussion of the Prior Art
Gas has long been a preferred fuel for heating water for both industrial and domestic use. An early arrangement for gas water heaters was simply to dispose a burner below a water tank, and to allow the flue gases to flow around the tank so the tank, and the water within, will absorb heat from the flue gases. Later water heaters have had an opening through the center of the tanks so flue gases pass both around the outside and through the center of the tank, giving more surface area for absorption of heat from the flue gases.
Even though a generous surface is provided for absorbing heat into the tank from the flue gases, the gases still pass quickly from the burner to the flue due to the high temperature of the gas. Thus, there have been additional efforts at capturing more of the heat, such additional efforts comprising the use of baffles in the vicinity of the tank, the idea being that the baffles retard the flow of flue gas to prevent laminar flow, and to allow more time for the gas to stay in contact with the tank so the tank will absorb more of the heat. The use of baffles and the like surely increase the efficiency of the water heating somewhat, but the baffles are complex and expensive to install, and provide additional surfaces for the accumulation of soot. A coating of soot of course acts as an insulator and inhibits the absorption of heat by the water tank. Thus, some means is still needed to extract the maximum heat from the flue gases without undue complexity.